Method for increasing the yield of fruit juice in the extraction of fruit juice concentrate

ABSTRACT

The invention concerns in general a method for the extraction of fruit juice concentrate, to produce a higher yield of fruit juice than that achieved by known methods. For this purpose juice is first extracted from the fruits in a juice extraction unit ( 1 ), producing a mixture of pulp and fruit juice. This mixture of pulp and fruit juice is then divided into pulp and primary juice ( 2 ). This pulp is then separated into pulp residues and secondary juice ( 7 ). The secondary juice is then pasteurised ( 8 ) and mixed with the primary juice. This mixture of primary juice and secondary juice is finally further processed into fruit juice concentrate

The invention relates in general to a method for extracting fruit juiceconcentrate and in particular to a method for increasing the yield offruit juice in the extraction of fruit juice concentrate from citrusfruits.

Fruit juices are unfermented, but fermentable, alcohol-free productsmade above all from pomaceous fruits, grapes and citrus fruits, whichpossess the characteristic aroma, the characteristic taste and thecharacteristic colour of the juices concerned. The juices are extractedby mechanical means from fresh fruit or fruit made non-perishable bychilling, from which coarse and/or indigestible parts, such as forexample peel and seeds have been removed, and which have been madenon-perishable by physical. methods.

One problem with the production of fruit juices lies in the fact thatafter the comminution of the fruit by technical means in the productionprocess (e.g. during juice extraction) uncontrolled enzyme and otherreactions set in, as the destruction of the cells means that enzymes andother constituents are no longer separated from each other by the cellmembranes.

One possibility of preventing these undesired reactions is by producinga fruit juice concentrate. For this purpose the mixture of pulp andfruit juice resulting after juice extraction is separated into fruitjuice and pulp (fruit flesh) by means of a passing machine. The fruitjuice is then processed by concentration to give fruit juiceconcentrate. The pulp can be made non-perishable by heat treatment andcooling or aseptic packaging. By means of these suitable processingsteps the abovementioned reactions can be prevented. The restoration ofthe fruit juice is carried out by means of a re-dilution procedure, inwhich the quantity of water removed during concentration is put backinto the fruit juice concentrate. In addition, part or all of the pulpremoved during concentration can be admixed again.

Moreover producing the fruit juice concentrate in the producer countryand subsequently re-diluting it in the consumer country results in aconsiderable reduction in transport costs, as the volume and weight ofthe concentrate are considerably lower than those of the actual fruitjuice.

The extraction of fruit juice concentrate from citrus fruits is carriedout by a known method, in which fruits are separated into severalconstituent groups in a juice extraction plant, i.e. into peel, zest,seeds and oil emulsion on the one hand, and into pulp and fruit juice onthe other hand. This mixture of pulp and fruit juice is then fed into apassing machine where it is divided into pulp and primary juice. Theprimary juice is then further processed to produce fruit juiceconcentrate by a known method.

In a further process step the pulps produced during passing aresubmitted to pulp extraction, in which, with the addition of water, onthe one hand pulp extract and on the other hand pulp residues areproduced. These pulp residues are waste materials and are of no furtheruse for drinks production. There are therefore for the most part driedand further processed, for example, into animal fodder or fertilizers.

The pulp extract is then fed into an evaporator. The aim of this processstep is to thicken the pulp extract, and so the condensate is removedfrom the pulp extract. The pulp extract concentrated in this way is notsuitable for the production of fruit juice and is mostly used as a basematerial for refreshing drinks.

This known method has several disadvantages:

During the pulp extraction stage, considerable quantities of juice arelost via the pulp residues, which could be used for fruit juice. Thisresults in substantial financial losses.

The resultant pulp extract and thus also the concentrated pulp extractcontain some constituents that adversely affect the taste of therefreshing drinks produced using the concentrated pulp extract.

In the known process, large quantities of residual fluid are produced.As explained above, a great deal of water has to be used in extractionof the pulp, and this water remains in the pulp residues following theextraction, or ends up as condensate after the evaporation of the pulpextract. The high water consumption and the high energy use in thesubsequent removal of the water in the drying of the pulp residuesand/or evaporation of the pulp extract give rise to high productioncosts. No further fruit juice is extracted in the process.

Finally it is desirable to minimise the quantity of concentrated pulpextract produced. There are good economic reasons for not producing anypulp extract, but for extracting the high quality residual juicecontained in the pulp and using this in the production of fruit juiceconcentrate.

Consequently, it is the object of the present invention to provide amethod for the production of fruit juice concentrate, in which the yieldof usable fruit juice is increased and the quantity of residual fluidand waste materials is minimised.

The abobe object is fulfilled by the features of claim 1. Advantageousdevelopments of the present invention are subject-matter of thesub-claims.

The present invention is now described on the basis of an example withreference to the attached drawings; these show:

FIG. 1 a diagrammatic representation of the process steps in a usualprocess for the production of fruit juice concentrate; and

FIG. 2 a diagrammatic representation of the process according to theinvention for the production of fruit juice concentrate.

In the following, reference is made to FIG. 1, in which the knownprocess for the production of fruit juice concentrate is represented.First of all, fruit that have suffered attack by microbes (rotten fruit)are picked out. The remaining citrus fruits, to be processed into fruitjuice concentrate, are then cleaned and fed into a juice extraction unit1. There the juice is extracted from the citrus fruits and they areseparated into two main groups of constituents. The first groupcomprises peel, zest, seeds and oil emulsion. The second group comprisesa mixture of pulp and fruit juice.

This mixture of pulp and fruit juice is then fed into a passing machine2 where it is divided into primary juice and pulp.

The primary juice is fed into an evaporator 3, where it is thickened. Inthis process step fruit juice concentrate is produced with condensate asa waste product. The fruit juice concentrate can now be stored inlow-temperature tanks or put into drums. In these barrels it isdelivered to the juice producer, where the fruit juice concentrate isfurther processed to produce drinkable fruit juice.

The pulp separated in the passing machine 2 then goes to a pulpextraction unit 4, where, with the addition of water, pulp extract andpulp residues are produced. The pulp residues are of no further use indrinks production. They can therefore be dried and subsequently furtherprocessed, for example, into animal fodder.

The pulp extract produced in the pulp extraction unit 4 is fed into anevaporator 5. In this process step the pulp extract is thickened,producing condensate and concentrated pulp extract. The concentratedpulp extract is used as a base material for refreshing drinks.

FIG. 2 shows the method for the processing of citrus fruits according tothe invention. In this case too, the fruits are first sorted, cleanedand then fed into a fruit extraction unit 1. Just as in the processdescribed above, the citrus fruits are also separated into two mainconstituent groups, the first group consisting of peel, zest, seeds andoil emulsion and the second group a mixture of pulp and fruit juice.This mixture of pulp and fruit juice can be either fed into a tubularheater (not shown), where at temperatures of 90 to 115° C. and for aduration of 20-60 seconds enzymes that are detrimental to quality aredestroyed. To some extent lower temperatures above 50° C. are alreadysufficient to achieve denaturing and hence deactivation of the enzymesthat are detrimental to quality. The heating should take place asquickly as possible following the comminution/juice extraction of thefruits, so as to minimise the time for which the enzymes are active.Subsequently the mixture of pulp and fruit juice (either directly fromthe juice extraction unit or via the tubular heater) is fed into apassing machine 2 where it is divided into primary juice and pulp. Theprimary juice is conveyed to a buffer tank 6 and then further processedas explained later. On the way to the buffer tank 6 the primary juicecan be re-cooled (if it was heated before the passing machine) anddegassed. It is also possible to free the primary juice of microbes byheating to a high temperature for a short time (90-115° C. for 20-60seconds). Here too, to some extent lower temperatures above 50° C. arealready sufficient, to achieve denaturing and hence deactivation of theenzymes that are detrimental to quality. In this alternative too,heating should take place as quickly as possible after the passingmachine, so as to minimise the time for which the enzymes are active.

The pulp extracted by means of the passing machine 2 is a mixture ofpulp solids and fruit juice constituents remaining in these. The pulp ispassed to a decanter 7, where it is continuously separated into pulpresidues and secondary juice. Instead of the decanter 7, other knownforms of continuously operating centrifuges can also be used. The pulpresidues are removed via the decanter spiral discharge, then dried andfurther processed, for example, into animal fodder or used asfertilizer. The secondary juice from the decanter 7 can pass through oneof three possible process paths or a combination of these:

a) The first process path A is preferred in the case of secondary juiceswith a low bitter constituent content. As can be seen from FIG. 2, thesecondary juice directly after the decanter 7 goes on to pasteurisation8, which may take place, for example in a plate heater. The pasteurisedjuice is then conveyed to the buffer tank 6.

b) In the second process path B the secondary juice after the decanter 7is conveyed to a plate heater where it is submitted to pasteurisation 9.Subsequently the pasteurised secondary juice is conveyed to a centrifuge12, to separate fine sludge constituents from the secondary juice; theseare then conveyed to the buffer tank 6 in a certain dosage. Aftercentrifuging, the secondary juice, from which the sludge constituentshave been removed, is conveyed to a debitterisation system 13 anddebittered by means of an adsorption column. The juice thus debitteredis then fed into the primary juice already contained in the buffer tank6 in doses dependent on the quantity.

c) In the third process path C too, the secondary juice after thedecanter 7 is conveyed to a plate heater where it is submitted topasteurisation 10. The pasteurised secondary juice is then cooled downto the entry temperature for the evaporator 11 and worked up to asemi-concentrate (22 to 28 Brix). At the same time oil is removed duringthe evaporation process. The semi-concentrate is now conveyed to thecentrifuge 12, to separate fine sludge constituents from the secondaryjuice; these are then conveyed to the buffer tank 6 in a dosagedependent on quantity. After centrifuging, the secondary juice (i.e. thesemiconcentrate) from which the sludge constituents have been removed isalso conveyed to the debitterisation system 13 and debittered by meansof an adsorption column. The debittered juice is then fed into theprimary juice already contained in the buffer tank 6 in doses dependenton the quantity.

With regard to process path C, it should be noted that thesemi-concentrate after the evaporation process in the evaporator 11 doesnot need to be conveyed direct to the centrifuge 12. These two processsteps (evaporation and centrifuging) can also be carried out atdifferent sites. For this purpose, after evaporation, thesemi-concentrate can first be stored in low-temperature tanks or pouredaseptically into drums, which are then delivered to the juice producer,where the subsequent process steps are carried out.

The mixture of primary juice, further processed secondary juice andsludge constituents contained in the buffer tank 6 is then conveyed toan evaporator 3, where the juice is thickened. In this process stepfruit juice concentrate is produced, with condensate as a waste product.The fruit juice concentrate can now, as already explained above, bestored in low-temperature tanks or poured into drums and later furtherprocessed into drinkable fruit juice.

It should be noted that the buffer tank is not strictly necessary forthe process in itself. The primary juice and the secondary juicesfurther processed in the different process paths A, B and C can also beconveyed direct to the evaporator 3. The buffer tank 6 serves here onlyfor intermediate storage of juices that are not to be further processedimmediately.

What is claimed is:
 1. Method for the extraction of fruit juiceconcentrate, comprising the following steps: juice extraction (1) offruits, to produce a mixture of pulp and fruit juice, separation (2) ofthe mixture of pulp and fruit juice into pulp and primary juice,separation (7) of the pulp into pulp residues and secondary juice,pasteurization (8) of the secondary juice, admixture of the secondaryjuice to the primary juice, and further processing of the mixture ofprimary juice and secondary juice to give fruit juice concentrate. 2.Method according to claim 1, in which the separation of the pulp intopulp residues and secondary juice takes place with the aid of a decanter(7).
 3. Method according to claims 1 or 2, in which the pasteurizationof the secondary juice takes place as soon as the separation (7) of thepulp into pulp residues and secondary juice has taken place.
 4. Methodfor the extraction of fruit juice concentrate, comprising the followingsteps: juice extraction (1) of fruits, to produce a mixture of pulp andfruit juice, separation (2) of the mixture of pulp and fruit juice intopulp and primary juice, separation (7) of the pulp into pulp residuesand secondary juice, pasteurization (9) of the secondary juice,centrifuging (12) of the secondary juice, to separate sludgeconstituents, debitterisation (13) of the secondary juice from which thesludge constituents have been removed, admixture of the debitterisedsecondary juice and the sludge constituents to the primary juice, andfurther processing of the mixture of primary juice, debitterisedsecondary juice and sludge constituents to give fruit juice concentrate.5. Method according to claim 4, in which the separation of the pulp intopulp residues and secondary juice takes place with the aid of a decanter(7).
 6. Method according to claims 4 or 5, in which the pasteurizationof the secondary juice takes place as soon as the separation (7) of thepulp into pulp residues and secondary juice has taken place.
 7. Methodfor the extraction of fruit juice concentrate, comprising the followingsteps: juice extraction (1) of the fruits, to produce a mixture of pulpand fruit juice, separation (2) of the mixture of pulp and fruit juiceinto pulp and primary juice, separation (7) of the pulp into pulpresidues and secondary juice, pasteurization (10) of the secondaryjuice, evaporation (11) of the secondary juice, to producesemi-concentrate, centrifuging (12) of the semi-concentrate, to separatesludge constituents, debitterisation (13) of the semi-concentrate fromwhich the sludge constituents have been removed, admixture of thedebitterised semi-concentrate and the sludge constituents to the primaryjuice, and further processing of the mixture of the primary juice,debitterised semi-concentrate and sludge constituents to give fruitjuice concentrate.
 8. Method according to claim 7, in which theseparation of the pulp into pulp residues and secondary juice takesplace with the aid of a decanter (7).
 9. Method according to claims 7 or8, in which the pasteurization of the secondary juice takes place assoon as the separation (7) of the pulp into pulp residues and secondaryjuice has taken place.